<mat-input-container class="full-width">
  <input matInput type="text" placeholder="在这里快速建立一个任务" [(ngModel)]="desc" name="desc" required>
  <button matSuffix mat-icon-button type="button" (click)="onSubmit()"><mat-icon>send</mat-icon></button>
  <mat-error>不能为空</mat-error>
</mat-input-container>
